/* * linux/arch/m68k/mm/fault.c * * Copyright (C) 1995 Hamish Macdonald */ #include <linux/mman.h> #include <linux/mm.h> #include <linux/kernel.h> #include <linux/ptrace.h> #include <linux/interrupt.h> #include <linux/module.h> #include <asm/setup.h> #include <asm/traps.h> #include <asm/system.h> #include <asm/uaccess.h> #include <asm/pgalloc.h> extern void die_if_kernel(char *, struct pt_regs *, long); extern const int frame_extra_sizes[]; /* in m68k/kernel/signal.c */ int send_fault_sig(struct pt_regs *regs) { siginfo_t siginfo = { 0, 0, 0, }; siginfo.si_signo = current->thread.signo; siginfo.si_code = current->thread.code; siginfo.si_addr = (void *)current->thread.faddr; #ifdef DEBUG printk("send_fault_sig: %p,%d,%d\n", siginfo.si_addr, siginfo.si_signo, siginfo.si_code); #endif if (user_mode(regs)) { force_sig_info(siginfo.si_signo, &siginfo, current); } else { const struct exception_table_entry *fixup; /* Are we prepared to handle this kernel fault? */ if ((fixup = search_exception_tables(regs->pc))) { struct pt_regs *tregs; /* Create a new four word stack frame, discarding the old one. */ regs->stkadj = frame_extra_sizes[regs->format]; tregs = (struct pt_regs *)((ulong)regs + regs->stkadj); tregs->vector = regs->vector; tregs->format = 0; tregs->pc = fixup->fixup; tregs->sr = regs->sr; return -1; } //if (siginfo.si_signo == SIGBUS) // force_sig_info(siginfo.si_signo, // &siginfo, current); /* * Oops. The kernel tried to access some bad page. We'll have to * terminate things with extreme prejudice. */ if ((unsigned long)siginfo.si_addr < PAGE_SIZE) printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference"); else printk(KERN_ALERT "Unable to handle kernel access"); printk(" at virtual address %p\n", siginfo.si_addr); die_if_kernel("Oops", regs, 0 /*error_code*/); do_exit(SIGKILL); } return 1; } /* * This routine handles page faults. It determines the problem, and * then passes it off to one of the appropriate routines. * * error_code: * bit 0 == 0 means no page found, 1 means protection fault * bit 1 == 0 means read, 1 means write * * If this routine detects a bad access, it returns 1, otherwise it * returns 0. */ int do_page_fault(struct pt_regs *regs, unsigned long address, unsigned long error_code) { struct mm_struct *mm = current->mm; struct vm_area_struct * vma; int write, fault; #ifdef DEBUG printk ("do page fault:\nregs->sr=%#x, regs->pc=%#lx, address=%#lx, %ld, %p\n", regs->sr, regs->pc, address, error_code, current->mm->pgd); #endif /* * If we're in an interrupt or have no user * context, we must not take the fault.. */ if (in_atomic() || !mm) goto no_context; down_read(&mm->mmap_sem); vma = find_vma(mm, address); if (!vma) goto map_err; if (vma->vm_flags & VM_IO) goto acc_err; if (vma->vm_start <= address) goto good_area; if (!(vma->vm_flags & VM_GROWSDOWN)) goto map_err; if (user_mode(regs)) { /* Accessing the stack below usp is always a bug. The "+ 256" is there due to some instructions doing pre-decrement on the stack and that doesn't show up until later. */ if (address + 256 < rdusp()) goto map_err; } if (expand_stack(vma, address)) goto map_err; /* * Ok, we have a good vm_area for this memory access, so * we can handle it.. */ good_area: #ifdef DEBUG printk("do_page_fault: good_area\n"); #endif write = 0; switch (error_code & 3) { default: /* 3: write, present */ /* fall through */ case 2: /* write, not present */ if (!(vma->vm_flags & VM_WRITE)) goto acc_err; write++; break; case 1: /* read, present */ goto acc_err; case 0: /* read, not present */ if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) goto acc_err; } /* * If for any reason at all we couldn't handle the fault, * make sure we exit gracefully rather than endlessly redo * the fault. */ survive: fault = handle_mm_fault(mm, vma, address, write); #ifdef DEBUG printk("handle_mm_fault returns %d\n",fault); #endif if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) goto out_of_memory; else if (fault & VM_FAULT_SIGBUS) goto bus_err; BUG(); } if (fault & VM_FAULT_MAJOR) current->maj_flt++; else current->min_flt++; up_read(&mm->mmap_sem); return 0; /* * We ran out of memory, or some other thing happened to us that made * us unable to handle the page fault gracefully. */ out_of_memory: up_read(&mm->mmap_sem); if (is_global_init(current)) { yield(); down_read(&mm->mmap_sem); goto survive; } printk("VM: killing process %s\n", current->comm); if (user_mode(regs)) do_group_exit(SIGKILL); no_context: current->thread.signo = SIGBUS; current->thread.faddr = address; return send_fault_sig(regs); bus_err: current->thread.signo = SIGBUS; current->thread.code = BUS_ADRERR; current->thread.faddr = address; goto send_sig; map_err: current->thread.signo = SIGSEGV; current->thread.code = SEGV_MAPERR; current->thread.faddr = address; goto send_sig; acc_err: current->thread.signo = SIGSEGV; current->thread.code = SEGV_ACCERR; current->thread.faddr = address; send_sig: up_read(&mm->mmap_sem); return send_fault_sig(regs); }